Brazing solder



Patented Mar. 9,1937

UNITED STATES PATENT OFFICE a aaazmo somm cy ri sameysmimcnamm uunuu' American Brass'Oo mpany, Waterbury,

Coma, a corporation of Connecticut No Drawing. Application May 18, 1082.

Serial No. 612,158

2 Claims. (01. 75-154) 10 of lowest melting point (ternary eutectic) con-.

tains in the neighborhood of 5 percent phos-.

phorus and 15 percent tin and this melts at about 647 C. Smaller additions of tin are propor-' tionally effective in lowering the melting point 15 and result in a cheaper alloy. The particular advantage of the new alloys and especially of the ternary eutectic lies in their low melting points which render theiruse especially desirable in those structures which excessive heat 20 would damage either by its weakening eifect on the metal or by warping. Moreover, the low temperature needed permits use of a simple form of torch or other heating device.

The amounts of tin and phosphorus may be 25 varied so that the :alloy approximates to the binary eutectic valley in the solid model of the ternary equilibrium (11 8mm, which curve is roughly defined by compositions in which the phosphorus content plus the tin content divided by 4.4 equals approximately 8.4'percent, or stating it in the form of an equation 7 qP+---' ai -g4. Thus ifthe alloy containsiipercent phosphorus -35-andl5percentti nwehave welding lies within the range where the percent phosphorus plus the percentage of tin divided by 4.4 lies between 3 and 10, the amount of tin being from 1 percent to 20 percent.

7 The alloys as above decribed have been satisfactorily used for soldering non-ferrous metals and alloys and have also been used for soldering steel, although in the latter case the formation of iron-phosphides at the surface of the steel renders the joint excessively brittle. The alloys may be'used in the form of castrodsor in the granulated condition with or without suitable admixture of flux. Certain of the alloys may be hot worked to form rod or wire'but this is a difficult operation d in generarthe cast or is granulated form is referred. If the surfaces to be joined are clean no flux is. necessary, but the use of flux is advisable. The melting point ofthe alloy is too low for the use ofborax alone,

but borax with a suitable addition, such as sodium fluoride or zinc chloride to reduce the meltin point may be used.

The presence of the usual impurities such as iron, zinc, lead and so forth in commercial alloys does not modify the action of the solder. I have also found that small additions of cadmium; 7

- antimony and silicon are without deleterious eflects, but aluminum and magnesium form tenacious oxide films and interfere with the running qualities. 0

The high fluidity and low melting point of. the alloys also renders .them suitable for the.

' manufacture of die castings and castings in per manent molds, especially in those cases where an.accurate finish is desired and high ductility is not of great importance.

Having thus set forth the nature of my invention, what I claim is: i

l. A brazing solder composed of tin from 13% to 17%, phosphorus from 3.5% to 5.5%, and the 404 balance copper.

2. A brazing solder composed of approximately 15% tin. 5% phosphorus, and copper. serlesofalloyswhichareusei'ulforsolderingor v 

